Cyber Incident Blamed for Nuclear Power Plant Shutdown

A nuclear power plant in Georgia was recently forced into an emergency shutdown for 48 hours after a software update was installed on a single computer.

The incident occurred on March 7 at Unit 2 of the Hatch nuclear power plant near Baxley, Georgia. The trouble started after an engineer from Southern Company, which manages the technology operations for the plant, installed a software update on a computer operating on the plant's business network.

The computer in question was used to monitor chemical and diagnostic data from one of the facility's primary control systems, and the software update was designed to synchronize data on both systems. According to a report filed with the Nuclear Regulatory Commission, when the updated computer rebooted, it reset the data on the control system, causing safety systems to errantly interpret the lack of data as a drop in water reservoirs that cool the plant's radioactive nuclear fuel rods. As a result, automated safety systems at the plant triggered a shutdown.

Southern Company spokeswoman Carrie Phillips said the nuclear plant's emergency systems performed as designed, and that at no time did the malfunction endanger the security or safety of the nuclear facility.

Phillips explained that company technicians were aware that there was full two-way communication between certain computers on the plant's corporate and control networks. But she said the engineer who installed the update was not aware that that the software was designed to synchronize data between machines on both networks, or that a reboot in the business system computer would force a similar reset in the control system machine.

"We were investigating cyber vulnerabilities and discovered that the systems were communicating, we just had not implemented corrective action prior to the automatic [shutdown]," Phillips said. She said plant engineers have since physically removed all network connections between the affected servers.

Computer security experts say the Hatch plant incident is the latest reminder of problems that can occur when corporate computer systems at the nation's most critical networks are connected to sensitive control systems that were never designed with security in mind.

Specifically, experts worry that vulnerabilities were introduced into the systems that regulate the electrical grid as power companies transferred control of generation and distribution equipment from internal networks to supervisory control and data acquisition, or SCADA, systems that can be accessed through the Internet or by phone lines, according to consultants and government reports.

The move to SCADA systems boosts efficiency at utilities because it allows workers to operate equipment remotely. But experts say it also exposes these once-closed systems to cyber attacks.

"Part of the challenge is we have all of this infrastructure in the control systems that was put in place in the 1980s and '90s that was not designed with security in mind, and all of sudden these systems are being connected to [Internet-facing] business networks" said Brian Ahern, president and chief executive of Industrial Defender Inc., a Foxborough, Mass.-based SCADA security company.

Joe Weiss, managing partner at Cupertino, Calif.-based Applied Control Solutions, said Hatch is not the only plant that has suffered this type of unusual event. But he said it is one of a handful of public events of this type because the Nuclear Regulatory Commission documents all unusual events, in contrast to non-nuclear facilities that do not make their unusual events public.

"Consequently, it is expected that non-nuclear facilities have experienced similar events," Weiss said. "The Hatch event illustrates the unintended consequences that could occur when business information technology systems interconnect with industrial control systems without adequate design considerations."